GNGTS 2013 - Atti del 32° Convegno Nazionale

input data to obtain in this way the crustal field. This crustal field represents the magnetization content in the continental and oceanic lithosphere at satellite altitude and its values do not reach absolute values higher than 20 nT. Then, we used these residual values to model the crustal field using a no-time-dependent model with K INT = 35 ( n k is approximately 65). In this model we apply the spatial regularization norm with damping parameter equal to 10 -5 nT -2 and the approach is not iterative. The penalized B-cube splines are not used in this part of the work as well as the constraint of the temporal norm of the geomagnetic field. The results are plotted in Figs. 1 and 2. The Fig. 1 shows two different profiles at 450 km of altitude in the north-south and west-east directions centered at 45ºN, 43ºE. We have chosen this value of altitude because is approximately the mean altitude of the different satellite orbits. For comparison we also show the model prediction of the CHAOS-4 model (Olsen et al. , 2010). This global model was developed by using the same set of satellite data including ground data Fig. 1 – Model prediction (red) at 450 km from Earth’s surface at 45°N (a) and 15°E (b) compared with CHAOS-4 model (in blue). 167 GNGTS 2013 S essione 3.2